Air compressor having tilted piston

ABSTRACT

An air compressor includes a cylinder housing having an outlet tube and an inner peripheral surface, a piston slidably received in the cylinder housing and having a piston rod, the piston is tilted relative to a longitudinal or lateral axis T of the piston rod, and a motor is coupled to the piston for moving the piston relative to the cylinder housing in a reciprocating action in order to generate pressurized air. The piston rod is tilted relative to the longitudinal axis Z of the cylinder housing, and the piston is arranged to be perpendicular to the longitudinal axis Z and the inner peripheral surface of the cylinder housing when the piston is moved toward the outlet tube in a pumping stroke for effectively compressing and pumping the air in the cylinder housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air compressor, and more particularly to an air compressor having a tilted piston for effectively compressing or pumping the air in the pumping movement or stroke and/or for suitably increasing the compressing or pumping effect or operation to the air.

2. Description of the Prior Art

Typical air compressors comprise a cylinder housing attached or secured to a base and having a piston slidably disposed therein, and a motor secured to the base and coupled to the piston of the cylinder housing for actuating or driving the piston of the cylinder housing in a reciprocating action, in order to generate a pressurized air of a greater air pressure and a decreased flowing quantity and for supplying the pressurized air to inflate various air facilities, such as tires, air beds, air cushions, hovercrafts, etc.

The cylinder housing normally includes an outlet tube having one or more outlet ports for selectively attaching and securing or coupling various parts or elements or attachments or facilities, such as the pressure gauges, the air nozzles, the relief valves, the safety valves or the like.

The applicant has developed various kinds of typical air compressors, including at least U.S. Pat. No. 6,213,725 to Chou, U.S. Pat. No. 6,514,058 to Chou, U.S. Pat. No. 6,655,928 to Chou, U.S. Pat. No. 6,846,162 to Chou, U.S. Pat. No. 7,240,642 to Chou, and U.S. Pat. No. 7,462,018 to Chou each of which also comprise a piston slidably disposed within a cylinder housing, a spring valve having one end secured to the piston and having the other end for selectively blocking an air aperture of the piston, in order to control the air to flow through the piston, and a motor secured to the base and coupled to the piston of the cylinder housing for actuating or driving or forcing the piston of the cylinder housing to move in the reciprocating action relative to the cylinder housing.

Normally, an eccentric member is rotatably attached to the cylinder housing or a supporting plate and coupled to the piston for actuating or driving or forcing the piston to move relative to the cylinder housing, and the piston will be tilted relative to the cylinder housing particularly when the piston is forced to move into the cylinder housing in the compressing or pumping movement or stroke.

However, all the pistons of prior arts include a piston rod extended therefrom, the piston rod includes a longitudinal axis and a lateral axis perpendicular with each other and passing through the orifice of the piston rod, but the piston is always parallel to the lateral axis and is simultaneously perpendicular to the longitudinal axis, while in use, particularly when the piston is forced to move into the cylinder housing in the compressing or pumping movement or stroke, the piston will be tilted relative to the cylinder housing and may not effectively compress or pump the air in the pumping movement or stroke.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional pistons for the air compressors.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide an air compressor including a tilted piston for effectively compressing or pumping the air in the pumping movement or stroke and/or for suitably increasing the compressing or pumping effect or operation to the air.

In accordance with one aspect of the invention, there is provided an air compressor comprising a cylinder housing including a chamber formed therein, and including an inner peripheral surface formed therein, and including an outlet tube having a compartment formed therein and communicating with the chamber of the cylinder housing for receiving a pressurized air from the chamber of the cylinder housing, and including a supporting plate, and including a longitudinal axis Z, a piston slidably received in the chamber of the cylinder housing and having a piston rod extended therefrom, the piston rod including a longitudinal axis L and a lateral axis T perpendicular with each other, and the piston being tilted relative to the longitudinal axis L and the lateral axis T of the piston rod, and a motor attached to the supporting plate and coupled to the piston for moving the piston relative to the cylinder housing in a reciprocating action in order to generate the pressurized air.

The piston is tilted relative to the lateral axis T of the piston rod for a non-zero angle θ ranged between 0 and 45 degrees (0°<θ<45°, and preferably ranged between 2 and 10 degrees (2°<θ<10°), the piston rod is tilted relative to the longitudinal axis Z of the cylinder housing, and the piston is arranged to be perpendicular to the longitudinal axis Z and the inner peripheral surface of the cylinder housing when the piston is moved toward the outlet tube in a pumping stroke for effectively compressing and pumping an air in the chamber of the cylinder housing.

The cylinder housing includes an end surface formed therein and tilted relative to the longitudinal axis Z and the inner peripheral surface of the cylinder housing. The piston includes an air passage formed therein, and includes a valve device attached to the piston for biasing and blocking the air passage of the piston and for controlling the air to flow through the air passage of the piston. The valve device includes a first side attached to the piston, and a second side movable away from the piston.

The valve device includes an opening form in the second side thereof, and the piston includes a limiting device extended from the piston and extended through the opening of the valve device for engaging with the second side of the valve device and for limiting the second side of the valve device to move relative to the piston, and for preventing the second side of the valve device from being over bent relative to the valve device. The cylinder housing includes a cavity formed therein for selectively receiving and engaging with the limiting device.

The cylinder housing includes a valve seat provided in the outlet tube and located between the outlet tube and the cylinder housing, and a spring-biased check valve disposed in the outlet tube and engaged with the valve seat to limit the pressurized air to flow from the chamber of the cylinder housing into the compartment of the outlet tube only, and to prevent the pressurized air from flowing backwardly from the compartment of the outlet tube into the chamber of the cylinder housing.

The motor includes a spindle extended through the supporting plate, and an eccentric member coupled to the spindle and having a pin coupled to the piston rod for moving the piston relative to the cylinder housing. The supporting plate includes a gear rotatably attached thereto and having a space formed by a peripheral casing to receive the eccentric member.

The cylinder housing includes a first duct, a second duct, and at least one third duct extended outwardly from the outlet tube and communicating with the compartment of the outlet tube for receiving the pressurized air from the outlet tube, a pressure gauge attached to the first duct, a nozzle coupled to the second duct, and a relief valve attached to the at least one third duct.

Further objectives and advantages of the present invention will become apparent from a careful reading of the detailed description provided hereinbelow, with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial exploded view of an air compressor in accordance with the present invention;

FIG. 2 is a perspective view of the air compressor;

FIG. 3 is a plan schematic view of the air compressor, in which a portion of the air compressor has been cut off for showing the inner structure of the air compressor;

FIG. 4 is another plan schematic view similar to FIG. 3, illustrating the operation of the air compressor;

FIG. 5 is a further plan schematic view illustrating the supporting base and the cylinder housing of the air compressor;

FIG. 6 is a still further plan schematic view as seen from the other direction of the supporting base and the cylinder housing of the air compressor;

FIG. 7 is a perspective view illustrating the piston and the piston rod of the air compressor;

FIG. 8 is another perspective view similar to FIG. 7, illustrating the operation of the piston for the air compressor;

FIG. 9 is a partial cross sectional view of the piston and the piston rod, taken along lines 9-9 of FIG. 7;

FIG. 10 is a plan schematic view of the piston and the piston rod;

FIGS. 11, 12, 13, 14, 15, 16 are plan schematic views similar to FIG. 3, illustrating the operation of the air compressor;

FIG. 17 is a further partial exploded view illustrating the other arrangement of the air compressor;

FIG. 18 is a perspective view of the air compressor as shown in FIG. 17; and

FIG. 19 is a partial exploded view illustrating the further arrangement of the supporting base and the cylinder housing for the air compressor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, and initially to FIGS. 1-6, an air compressor in accordance with the present invention comprises a supporting base 10 including a supporting plate 11 and a cylinder housing 20 provided on or extended from the supporting plate 11 and preferably, but not necessarily formed integral with the supporting plate 11, for example, the supporting plate 11 and the cylinder housing 20 may be formed integral with each other with the molding or mold-injection processes as shown in FIGS. 1-6, or alternatively, as shown in FIG. 19, the cylinder housing 200 may include one or more projections 201 extended therefrom and engaged with corresponding hubs or tubular members 111 of the supporting plate 110 for detachably attaching or mounting or securing the cylinder housing 200 to the supporting plate 110.

As also shown in FIGS. 1-6, the supporting plate 11 includes two holes 12, 13, such as an upper hole 12 and a lower hole 13 formed therein, in which the upper hole 12 of the supporting plate 11 is located closer to the cylinder housing 20, and the lower hole 13 of the supporting plate 11 is located distal or farther away from the cylinder housing 20. The cylinder housing 20 includes a chamber 21 formed therein and formed or defined by an inner peripheral surface 22 for slidably receiving or engaging with a piston 30 therein, the piston 30 includes an extension or piston rod 31 extended therefrom and is slidable in a reciprocating action in the chamber 21 of the cylinder housing 20 for generating pressurized air.

The cylinder housing 20 includes an outlet tube 15 extended upwardly or outwardly from the top thereof, and having a compartment 16 formed therein (FIGS. 3-4, 11-16) and communicating with the chamber 21 of the cylinder housing 20, for receiving the pressurized air from the chamber 21 of the cylinder housing 20. A spring-biased check valve 17 (FIGS. 3-4, 11-16) may be disposed in the outlet tube 15, and engaged with a valve seat 18 that is formed or provided between the outlet tube 15 and the cylinder housing 20. A relief valve or safety valve (not shown) or the like may further be provided and attached to the outlet tube 15, for relieving the pressurized air when the air pressure within the cylinder housing 20 and the outlet tube 15 is over a predetermined value.

The spring-biased check valve 17 may thus be used to limit and to guide the pressurized air to flow only from the chamber 21 of the cylinder housing 20 into the compartment 16 of the outlet tube 15, and to prevent the pressurized air from flowing backwardly from the compartment 16 of the outlet tube 15 into the chamber 21 of the cylinder housing 20. A cap 19 may further be provided and attached to the outer or free end of the outlet tube 15 with such as a threading engagement (not shown) for blocking or enclosing or sealing the compartment 16 of the outlet tube 15, and for stably retaining the spring-biased check valve 17 within the compartment 16 of the outlet tube 15.

The cylinder housing 20 further includes one or more ducts 23, 24, 25, 26 extended outwardly from the outlet tube 15, and communicating with the compartment 16 of the outlet tube 15, for receiving the pressurized air from the compartment 16 of the outlet tube 15. The ducts 23, 24, 25, 26 may be coupled to various kinds of facilities that require pressurized air supplied thereto. For example, a relief valve 27 (FIG. 19) may be provided and attached to one of the ducts 23 for relieving the pressurized air when the air pressure within the cylinder housing 20 and/or the outlet tube 15 is over a predetermined pressure, and thus for preventing the cylinder housing 20 and/or the outlet tube 15 from being over-pressurized and damaged.

A pressure gauge 28 may be provided and attached to the other duct 24 for detecting and showing the air pressure within the cylinder housing 20 and/or the outlet tube 15. A nozzle 29 may be provided and attached to another duct 26 for allowing the pressurized air to be supplied from the chamber 21 of the cylinder housing 20 and the compartment 16 of the outlet tube 15 to various pneumatic facilities that require pressurized air supplied thereto, with the nozzle 29. A relief valve or safety valve 14 or the like may further be provided and attached to the other duct 25, for relieving the pressurized air when the air pressure within the cylinder housing 20 and the outlet tube 15 is over a predetermined value.

It is to be noted that the provision or the extension of the ducts 23, 24, 25, 26 from the outlet tube 15 allows the relief valve 27 and the pressure gauge 28 and the nozzle 29 to be easily and readily attached to or coupled to the outlet tube 15 with the ducts 23, 24, 25, 26, without additional or specialized coupling members or tools. One or more lids (not shown) may further be provided and attached or secured to either of the ducts 23, 24, 25, 26 with such as a threading engagement, for selectively enclosing or blocking the ducts 23, 24, 25, 26, when the ducts 23, 24, 25, 26 are not required to be used, or when the relief valve 27 and the pressure gauge 28 and the nozzle 29 are not attached or secured to the ducts 23, 24, 25, 26.

A gear 40 is rotatably attached to the lower portion of the supporting plate 11 with one or more bearings (not shown) and a shaft 41, and includes a space 43 formed therein and defined by a peripheral casing 44 for receiving and securing an eccentric member 45 therein. The eccentric member 45 may be secured to the gear 40 with such as fasteners (not shown) or with the molding or mold-injection processes and may thus be rotated in concert with the gear 40, and includes a crank or an eccentric pin 46 extended therefrom and coupled to the piston rod 31 of the piston 30, such as coupled to an orifice 39 of the piston rod 31 in order to actuate or to move the piston 30 relative to the cylinder housing 20 in reciprocating actions, the piston rod 31 includes a longitudinal axis L and a lateral axis T perpendicular with each other and passing or extended through the orifice 39 of the piston rod 31.

A motor 47 may be attached or secured to the upper portion of the supporting plate 11 with such as fasteners (not shown), and includes a spindle 48 extended through the upper hole 12 of supporting plate 11 (FIG. 2), and includes a pinion 49 secured to the spindle 48 thereof, and engaged with the gear 40, for allowing the gear 40 to be rotated or driven by the motor 47 with the pinion 49, and thus for allowing the piston 30 to be actuated or moved relative to the cylinder housing 20 in reciprocating actions by the eccentric member 45 and the eccentric pin 46. A fan device 42 may further be provided and coupled to the motor 47 for being rotated or driven by the motor 47 to generate circulating or ventilating air.

In operation, as shown in FIGS. 3 and 4, the piston 30 may be actuated or moved relative to the cylinder housing 20 in reciprocating actions by the motor 47 with the pinion 49, the gear 40, the eccentric member 45 and the eccentric pin 46, in order to generate a pressurized air, and to allow the pressurized air to flow into the outlet tube 15, and then to flow out through either or all of the ducts 23, 24, 25, 26, and thus to allow the air pressure within the cylinder housing 20 and/or the outlet tube 15 to be detected and shown by the pressure gauge 28, and to allow the pressurized air to be supplied into the facilities that require pressurized air supplied thereto, with the nozzle 29, and/or to allow the pressurized air to be relieved via the relief valve 27 when the cylinder housing 20 and/or the outlet tube 15 is over-pressurized.

Alternatively, as shown in FIGS. 17 and 18, another motor 471 of different dimension or power may be changeably attached or secured to the supporting plate 11 and extended through the lower hole 13 of supporting plate 11 and directly attached or mounted or secured to the eccentric member 450 with such as fasteners 451 for directly actuating or rotating or driving the eccentric member 450 to rotate relative to the cylinder housing 20 in reciprocating actions without the gear 40. The above-described structure including the supporting base 10, the supporting plate 11, the cylinder housing 20, the pressure gauge 28, the nozzle 29, the motor 471 and the eccentric member 450 is typical and will not be described in further details.

As shown in FIGS. 3-4 and 7-10, the piston 30 preferably includes a sealing ring 32 attached to the outer peripheral portion thereof and slidably engaged with the cylinder housing 20, for making an air tight seal between the piston 30 and the cylinder housing 20; and includes an air passage 33 formed therein. A spring blade or valve device 60 includes one or first side 61 attached or secured to one or first side 34 of the piston 30 with one or more latch pins or fasteners 62, and includes a suitable resilience for biasing and blocking the air passage 33 of the piston 30 and for controlling the air to selectively flow through the air passage 33 of the piston 30. The valve device 60 further includes an opening 63 form in the second side 64 of the valve device 60 and located opposite to or distal to the first side 61 of the valve device 60 and the fasteners 62, in which the second side 64 of the valve device 60 is movable away from the piston 30.

The valve device 60 is made of resilient metal or steel materials and may be forced to be bent relative to the piston 30 in order to block and to selectively open the air passage 33 of the piston 30 and to allow the air to flow through the piston 30 at one time when the air passage 33 of the piston 30 is partially opened by the spring blade or valve device 60. The piston 30 includes a limiting device or projection 35 extended upwardly from the second side 36 of the piston 30 and located opposite to the first side 61 of the valve device 60 and the fasteners 62, and preferably arranged to have the air passage 33 of the piston 30 formed and located between the fasteners 62 and the limiting device or projection 35.

The limiting device or projection 35 is extended through the opening 63 of the valve device 60 for engaging with the second side 64 of the valve device 60, and thus for limiting the second side 64 of the valve device 60 to bend or to move relative to the piston 30, and for preventing the second side 64 of the valve device 60 from being over bent or deformed relative to the first side 61 of the valve device 60. The fasteners 62 and the limiting device or projection 35 are particularly designed and provided for engaging with the valve device 60 as shown in FIGS. 4 and 7-9, and for preventing the valve device 60 from being over bent or deformed relative to the first side 61 of the valve device 60. The other valve devices may be attached to the piston 30 without the fasteners 62 and the limiting device or projection 35.

As also shown in FIGS. 4 and 7-10, the piston 30 is arranged and tilted relative to the longitudinal axis L or the lateral axis T of the piston rod 31 for a non-zero angle θ ranged between 0 and 45 degrees (0°<θ<45°, and preferably ranged between 2 and 10 degrees (2°<θ<10°, and/or the piston 30 includes a flat surface or an actuating surface 37 tilted relative to the longitudinal axis L or the lateral axis T of the piston rod 31 for the non-zero angle θ for allowing the piston 30 and/or the actuating surface 37 of the piston 30 to be perpendicular to the longitudinal axis Z of the cylinder housing 20 or to be parallel to the lateral axis X of the cylinder housing 20 when the piston 30 is moved toward the outlet tube 15 in the pumping movement or stroke or operation, at this moment, the piston rod 31 is tilted relative to the longitudinal axis Z of the cylinder housing 20, but the piston 30 and/or the actuating surface 37 of the piston 30 is perpendicular to the longitudinal axis Z of the cylinder housing 20 or to be parallel to the lateral axis X of the cylinder housing 20, best shown in FIG. 12. It is preferable that the non-zero angle θ is greater when the piston rod 31 is shorter, and is smaller when the piston rod 31 is longer relatively.

As shown in FIGS. 3-4 and 11-16, it is preferable that the cylinder housing 20 includes an inclined upper or top or end surface 70 formed therein and tilted or inclined relative to the longitudinal axis Z or the lateral axis X of the cylinder housing 20 and also tilted or inclined relative to the inner peripheral surface 22 of the cylinder housing 20, and further includes one or more, such as two or more cavities 71, 72 formed therein for selectively receiving or engaging with the fasteners 62 and the limiting device or projection 35 when the piston 30 is completely moved into the chamber 21 of the cylinder housing 20 (FIGS. 13, 14). The inclined upper or end surface 70 of the cylinder housing 20 is arranged to be parallel to the upper actuating surface 37 of the piston 30 when the piston 30 is completely moved into the chamber 21 of the cylinder housing 20 at the top dead position (FIG. 14).

In operation, as shown in FIG. 11, the actuating surface 37 of the piston 30 is tilted relative to the longitudinal axis Z and the inner peripheral surface 22 or the lateral axis X of the cylinder housing 20, and the piston rod 31 is substantially parallel to the longitudinal axis Z or perpendicular to the lateral axis X of the cylinder housing 20 when the piston 30 is moved away from the outlet tube 15 and the upper or end surface 70 of the cylinder housing 20 at the lowest dead position. As shown in FIG. 12, when the piston 30 is moved toward the outlet tube 15 in the pumping movement or stroke or operation, the piston rod 31 will be tilted relative to the longitudinal axis Z of the cylinder housing 20, and the actuating surface 37 of the piston 30 will be perpendicular to the longitudinal axis Z and the inner peripheral surface 22 and parallel to the lateral axis X of the cylinder housing 20 such that the piston 30 may effectively compress or pump the air in the chamber 21 of the cylinder housing 20 and in the pumping movement or stroke in order to suitably increase the compressing or pumping effect or operation to the air.

As shown in FIGS. 13 and 14, when the piston 30 is completely moved into the chamber 21 of the cylinder housing 20, the upper actuating surface 37 of the piston 30 will be parallel to the upper or end surface 70 of the cylinder housing 20, at this moment, the fasteners 62 and the limiting device or projection 35 will be selectively received or engaged with the cavities 71, 72 of the cylinder housing 20 respectively for allowing the piston 30 to be completely moved into the chamber 21 of the cylinder housing 20 at the top dead position where the piston rod 31 is substantially parallel to the longitudinal axis Z or perpendicular to the lateral axis X of the cylinder housing 20 again.

As shown in FIGS. 15 and 16, in the relieving or air intake stroke, the piston rod 31 will be tilted relative to the longitudinal axis Z or the lateral axis X of the cylinder housing 20, and the actuating surface 37 of the piston 30 will also be tilted relative to the longitudinal axis Z or the lateral axis X of the cylinder housing 20 and will substantially parallel to the upper or end surface 70 of the cylinder housing 20 at this moment, such that the piston 30 may be arranged to be perpendicular to the longitudinal axis Z and the inner peripheral surface 22 and parallel to the lateral axis X of the cylinder housing 20 when the piston 30 is moved toward the outlet tube 15 in the pumping movement or stroke or operation, and such that the piston 30 may be used to effectively compress or pump the air in the chamber 21 of the cylinder housing 20 and in the pumping movement or stroke in order to suitably increase the compressing or pumping effect or operation to the air.

Accordingly, the air compressor in accordance with the present invention includes a tilted piston for effectively compressing or pumping the air in the pumping movement or stroke and/or for suitably increasing the compressing or pumping effect or operation to the air.

Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the detailed construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed. 

1. An air compressor comprising: a cylinder housing including a chamber formed therein, and including an inner peripheral surface formed therein, and including an outlet tube having a compartment formed therein and communicating with said chamber of said cylinder housing for receiving a pressurized air from said chamber of said cylinder housing, and including a supporting plate, and including a longitudinal axis Z, a piston slidably received in said chamber of said cylinder housing and having a piston rod extended therefrom, said piston rod including a longitudinal axis L and a lateral axis T perpendicular with each other, and said piston being tilted relative to the longitudinal axis L and the lateral axis T of said piston rod, and a motor attached to said supporting plate and coupled to said piston for moving said piston relative to said cylinder housing in a reciprocating action in order to generate the pressurized air.
 2. The air compressor as claimed in claim 1, wherein said piston is tilted relative to the lateral axis T of said piston rod for a non-zero angle θ ranged between 0 and 45 degrees (0°<θ<45°, and said piston rod is tilted relative to the longitudinal axis Z of said cylinder housing, and said piston is arranged to be perpendicular to the longitudinal axis Z and said inner peripheral surface of said cylinder housing when said piston is moved toward said outlet tube in a pumping stroke for effectively compressing and pumping an air in said chamber of said cylinder housing.
 3. The air compressor as claimed in claim 1, wherein said piston is tilted relative to the lateral axis T of said piston rod for a non-zero angle θ ranged between 2 and 10 degrees (2°<θ<10°).
 4. The air compressor as claimed in claim 1, wherein said cylinder housing includes an end surface formed therein and tilted relative to the longitudinal axis Z and said inner peripheral surface of said cylinder housing.
 5. The air compressor as claimed in claim 1, wherein said piston includes an air passage formed therein, said piston includes a valve device attached to said piston for biasing and blocking said air passage of said piston and for controlling the air to flow through said air passage of said piston.
 6. The air compressor as claimed in claim 5, wherein said valve device includes a first side attached to said piston, and a second side movable away from said piston.
 7. The air compressor as claimed in claim 6, wherein said valve device includes an opening form in said second side thereof, and said piston includes a limiting device extended from said piston and extended through said opening of said valve device for engaging with said second side of said valve device and for limiting said second side of said valve device to move relative to said piston, and for preventing said second side of said valve device from being over bent relative to said valve device.
 8. The air compressor as claimed in claim 7, wherein said cylinder housing includes a cavity formed therein for selectively receiving and engaging with said limiting device.
 9. The air compressor as claimed in claim 1, wherein said cylinder housing includes a valve seat provided in said outlet tube and located between said outlet tube and said cylinder housing, and a spring-biased check valve disposed in said outlet tube and engaged with said valve seat to limit the pressurized air to flow from said chamber of said cylinder housing into said compartment of said outlet tube only, and to prevent the pressurized air from flowing backwardly from said compartment of said outlet tube into said chamber of said cylinder housing.
 10. The air compressor as claimed in claim 1, wherein said motor includes a spindle extended through said supporting plate, and an eccentric member coupled to said spindle and having a pin coupled to said piston rod for moving said piston relative to said cylinder housing.
 11. The air compressor as claimed in claim 10, wherein said supporting plate includes a gear rotatably attached thereto and having a space formed by a peripheral casing to receive said eccentric member.
 12. The air compressor as claimed in claim 1, wherein said cylinder housing includes a first duct, a second duct, and at least one third duct extended outwardly from said outlet tube and communicating with said compartment of said outlet tube for receiving the pressurized air from said outlet tube, a pressure gauge attached to said first duct, a nozzle coupled to said second duct, and a relief valve attached to said at least one third duct. 